| 摘要 |
PURPOSE:To prevent the adverse influence by the ghost light generated in an optical fiber amplifier by branching received light to two signals at a prescribed ratio by an optical receiver having the optical fiber amplifier added with a rare earth element, emitting the one thereof to an optical delay circuit and the other to an amplifier circuit and providing a differential amplifier which outputs the difference between the outputs of both and the output signal. CONSTITUTION:The incident signal light on the optical receiver B is branched by a 2X2 star coupler 3 to the two signals which are respectively made incident on the optical amplifier circuit C and an optical delay line 4. While the optical fiber amplifier 8 amplifies the incident signal light and emits this light to an optical filter 9, the amplifier superposes the ghost light generated by multiple reflections between an incident terminal 8a and an exit terminal 8b as well. On the other hand, the delay time of the signal light of the optical delay line 4 is set the same as the delay time of the ghost light of the amplifier 8 and the ratio of the branching in the coupler 3 is also set according to the intensity of the light. The outputs from photodetectors 5, 10 of the two circuits are offset and adjusted in the differential amplifier 11 in this way and the component of the ghost light is not included in the received signal outputted from the amplifier 11. The signal having the good characteristics is thus obtd. |
